1. Field of the Invention
The present invention relates to a magnetic head, a head assembly, a magnetic recording/reproducing apparatus, and a manufacturing method therefor.
2. Description of the Related Art
In the field of magnetic recording/reproducing apparatuses such as hard disk drive (HDD), a number of magnetic disks being a recording medium are installed in order to meet the demand for improved recording density. The increase in number of the magnetic disks not only causes vibration and noise problem of the magnetic disk due to air turbulence, so-called windage, but also increases fluid loss occurring during rotation of the magnetic disk, so-called windage loss, which results in the necessity of increasing the power of a motor to be built in the apparatus.
In order to solve this problem, for example, Japanese Unexamined Patent Application Publication No. 2007-328880 discloses a technology in which in order to reduce the windage and windage loss, an air within an apparatus is replaced by a helium gas of a lower gas density and then the apparatus is completely sealed as a whole.
On the other hand, Japanese Patent Publication No. 004358700 discloses a technology in which in the process of recording given servo data in a servo region of a magnetic disk indicating a track address, an air within an apparatus is temporarily replaced by an inert gas of a low gas density such as helium, thereby reducing the windage and improving writing accuracy of the servo data.
According to the former technology, the helium gas is finally kept sealed within the apparatus, while according to the latter technology, since the inert gas is again replaced by an air after writing of the servo data, the air is finally sealed within the apparatus. If it is possible to achieve high airtightness so as not to let the gas leak out of the apparatus, it is apparent that the former technology is preferable in view of the technical effects, because the windage can be reduced even in a usual information reproducing and recording process, making it possible to improve reading and writing accuracy. Moreover, since undesirable chemical reaction can be prevented by sealing the inert gas into the apparatus, it is also possible to prevent corrosion of the magnetic head and the magnetic disk.
However, since the apparatus manufactured by the former technology has a case structure with high airtightness, there is a problem that a protective film of DLC (diamond-like carbon) formed on a magnetic medium-facing surface of a built-in magnetic head cannot be removed from the outside after assembly. This protective film, which is provided so as to protect the magnetic head from corrosive action due to a surfactant during a plurality of cleaning processes in a series of production processes, is substantially essential to the production processes.
However, if the inert gas is sealed within the apparatus using the above technology, the corrosive action after assembly of the apparatus can be sufficiently prevented, and as a result, the protective film becomes unnecessary. Because of its thickness, moreover, the protective film increases the magnetical distance between the surface of the magnetic disk and the magnetic medium-facing surface of the magnetic head, which may become an obstacle to performance improvement in recording and reproducing of information.